Process for the preparation of aromatic hydrocarbons containing monoethylenic unsaturated radicals

ABSTRACT

Process for the preparation of aromatic hydrocarbon compounds containing monoethylenically unsaturated radicals, which comprises reacting a monoethylenically unsaturated compound with an aromatic hydrocarbon compound in the presence of a palladium salt.

United States Patent Moritani et a].

[ 51 Jul 4, 1972 [54] PROCESS FOR THE PREPARATION OF AROMATICHYDROCARBONS CONTAINING MONOETHYLENIC UNSATURATED RADICALS [72]Inventors: Ichiro Moritani, Takaishi-shi; Yuzo Fujiwara, Oyonaka-shi,both of Japan [73] Assignee: Ube Industriee, Ltd., Nishihonmachi, UbeshiYamaguchi-ken, Japan [22] Filed: July 29, 1968 [21] Appl. No.: 748,222

260/592, 260/595, 260/613, 260/645, 260/646, 260/651, 260/668 C, 260/671A, 260/671 C [51] Int. Cl ..C07c 15/10 [58] Field of Search ..260/669,671, 671 A, 671 C, 260/671 B, 497, 497 A, 499, 668 C [56] ReferencesCited UNITED STATES PATENTS 3,479,392 11/1969 Stern et al ..260/497Primary Examiner-Curtis R. Davis Attorney-Wenderoth, Lind & Ponack [5 7]ABSTRACT Process for the preparation of aromatic hydrocarbon compoundscontaining monoethylenically unsaturated radicals,

which comprises reacting a monoethylenically unsaturated compound withan aromatic hydrocarbon compound in the presence of a palladium salt.

10 Claims, No Drawings PROCESS FOR THE PREPARATION OF AROMATICHYDROCARBONS CONTAINING MONOETHYLENIC UNSATURATED RADICALS Thisinvention relates to a process for the preparation of aromatichydrocarbons which contain monoethylenic unsaturated radicals, by thereaction of monoethylenically unsaturated compounds with aromatichydrocarbons, in the presence of a palladium salt, such as palladiumacetate.

It is known that the reaction of monoethylenically unsaturatedhydrocarbons with aromatic hydrocarbons produces aromatic hydrocarbonswhich contain monoethylenically saturated hydrocarbon substituent, bythe mechanism of an addition reaction. It is well known, for example,that ethylbenzene is formed from ethylene and benzene, and cumene, frompropylene and benzene.

We discovered an entirely novel process of forming aromatic hydrocarbonscontaining monoethylenically unsatu-' rated substituent, by reactingmonoethylenically unsaturated compounds with aromatic hydrocarbons, inthe presence of a palladium salt, as the result of our extensiveresearches on the art. In this novel reaction, the unsaturated radicalsin the monoethylenically unsaturated compounds employed remain as theyare after the compounds are bonded with aromatic hydrocarbons.Therefore, it appears that a substitution reaction takes place in thisprocess, in contrast to the conventional addition reaction. Thus thesubject reaction may hereinafter be referred to as substitutionreaction.

Accordingly, the invention relates to a process for the preparation ofaromatic hydrocarbons containing monoethylenic unsaturated radicals, byreacting a monoethylenically unsaturated compound with an aromatichydrocarbon in the presence of a palladium salt, to perform an entirelynovel substitution reaction between the two.

As the monoethylenically unsaturated compounds useful for the subjectprocess, the following may be named:

the compounds of the formula in which X is selected from the groupconsisting of hydrogen,

halogens, alkyls of one to four carbons, phenyl and alkylsubstitutedphenyls; and

Y is selected from the group consisting of hydrogen, alkyls of one tofour carbons, phenyl, alkyl-substituted phenyls, nitrile, alkoxies ofone to four carbons, halogens, alkoxycarbonyls, and alkanoyloxies of twoto four carbons:

and the compounds of the formula in which R is selected from alkylenesof three to ten carbons.

A more specific examples, the following monoethylenically unsaturatedcompounds are preferably used in the invention: ethylene, propylene,l-butene, 2-butene, iso-butene, l-pentene, styrene, a-methylstyrene,4-methylstyrene, 1,1-diphenylethylene, trans-stilbene, cyclohexene,cyclooctene, acrylonitrile, vinyl butyl ether, vinyl ethyl ether, vinylchloride, vinylidene chloride, vinyl fluoride, 1,2- dichloroethylene,acrylic acid ester of alkyl containing one to four carbons, methacrylicacid ester of alkyl containing one to four carbons, vinyl acetate, vinylpropionate, and the like.

The aromatic hydrocarbons useful for the invention can be represented bythe formula in which Z is selected from the group consisting ofhydrogen, alkyls of one to twelve carbons, nitro halogens, alkoxies ofone to twelve carbons, hydroxy, monoand di-alkylaminos, acylamines,carboxyl, alkoxycarbonyls, and nitrile, and n is 1 or 2.

Particularly preferred aromatic hydrocarbons include benzene, toluene,0- or mor p-xylene, ethylbenzene, cumene, nonylbenzene, nitrobenzene,chlorobenzene, bromobenzene, anisole, butoxybenzene, phenol, resorcin,cresol, N-tert.-butylaminobenzene, N,N-dimethyla.niline, acetanilide,benzoic acid, dimethyl terephathalate, benzonitrile, and the like.

The palladium salts useful for the invention include inorganic acidsalts such as divalent palladium halides, nitrate and sulfate, andaliphatic monocarboxylates of one to five carbons. In the invention,particularly palladium acetate is preferred, while palladium formate,propionate, butyrate, and valerate are equally useful. When inorganicacid salts of palladium such as chloride, nitrate and sulfate are used,it is recommended that an alkali metal salt of an aliphaticmonocarboxylic acid of one to five carbons, inter alia, sodium orpotassium acetate, should be concurrently used, so that a palladium saltof the aliphatic monocarboxylic acid can be formed in the reactionsystem. In that case, it is preferred to use at least equivalentquantity, particularly 2 5 equivalents, of an alkali metal salt of thealiphatic monocarboxylic acid of one to five carbons, to the inorganicacid salt of palladium employed.

In accordance with the invention, it is preferred to use such apalladium salt in a quantity of at least one-fourth mol, particularlyone-fourth to 1 mole, per mol of the monoethylenically unsaturatedcompound employed. The entire quantity of the palladium salt may beadded to the reaction system at once in advance of the reaction, or apredetermined portion thereof may be first added in advance of thereaction and the rest may be added stepwise or continuously, as thereaction progresses.

The preferred quantity of the aromatic hydrocarbon in the reactionsystem is at least 2 mols, particularly 4 l0 mols, per mol of themonoethylenically unsaturated compound, in order to preventobjectionable side reactions between the monoethylenically unsaturatedcompounds, such as dimerization.

In practicing the subject invention, it is discovered that the rate ofthe intended substitution reaction can be remarkably increased when thereaction is performed in an aliphatic monocarboxylic acid of one to fivecarbons, such as formic, acetic, monochloroacetic, trichloroacetic,trifluoroacetic, propionic, butyric, and valeric acids, etc. Therefore,it is generally preferred in practicing the subject invention, to employthose aliphatic monocarboxylic acids as the solvent.

It is of course permissible to perform the reaction using an excess ofthe above-described aromatic hydrocarbon, a part of which serves as thesolvent, together with an aliphatic .m ab yl ses d- The operationalprocedures of the reaction are not critical. Thus it is permissible, forexample, to mix simultaneously or by optional order, themonoethylenically unsaturated compound, aromatic hydrocarbon andpalladium salt (particularly palladium acetate, or a mixture which willform palladium 0 acetate in the reaction system). Or, a complex from the0 acid salt of palladium, and the monoethylenically unsaturatedcompound. The complex, either alone or in combination with themonoethylenically unsaturated compound, is contacted with an aromatichydrocarbon.

The reaction of this invention can be illustrated with general formulasas follows:

lOl043 0473 X l (lily-(1, X--(1II:CH-Y 2) n palladium Y salt CH=CH X X R$H=| =CHY :111

or Q (Z)n (Z)n (Z)n In the formulas above, X, Y, Z, R and n possess thesame significance as defined in the foregoing.

The typical products of the above reaction will be named hereinbelow, inthe purpose of explanation: styrene, a-methylstyrene, B-methylstyrene,aand ,B-cyano-styrene, 1,2-diphenylethylene (stilbene),l,l,2-triphenylethylene, 1,2-diphenylpropylene,l-phenyl-Z-tolylethylene, l-phenylcyclohexene, B- butoxystyrene,B-chlorostyrene, B-dichlorostyrene, B- fluorostyrene, methyl cinnamate,a-methyl cinnanmic acid methyl ester, B-acetoxystyrene,l-(2,5-dimethylphenyl)-2- phenylethylene,l-(ethylphenyl)-2-phenylethylene, l- (nitrophenyl)-2-tolylethylene,l-(chlorophenyl)-2-phenylethylene, l-(methoxyphenyl)-3-phenylethylene,l-(oxyphenyl)-2-tolylethylene, l-(dimethylaminophenyl)-2-phenylethylene,l-(dimethoxycarbonylphenyl)-2-phenylethylene, and the like.

In practicing the subject invention, other reaction conditions varyconsiderably, depending on the specific types of monoethylenicallyunsaturated compound, aromatic hydrocarbon and palladium salt. Generallyspeaking, however, the reaction proceeds under temperatures ranging fromroom temperature to 200 C., particularly 60 100 C. The pressurecondition is not critical, which may be atmospheric or elevated. Themanner of reaction neither is critical, which may be performed batchwiseor continuously.

The atmosphere of the reaction may be of the air, or of an inert gassuch as nitrogen or carbon dioxide. In the invention, the progress ofthe reaction can be easily observed since metallic palladiumprecipitates as the reaction proceeds. Normally the sufficient reactiontime is in the order of 30 minutes to hours.

According to the process of this invention, the palladium salt remainsafter the reaction in the form of metallic palladium (palladium black)precipitate, which is subsequently separated and recovered. Separationof the object compound from the reaction mixture is performed by themeans known per se. For example, preceding or after the recovery ofpalladium black from the reaction mixture, the unreactedmonoethylenically unsaturated compound and aromatic compound, as well asaliphatic monocarboxylic acid if employed in the reaction, are distilledoff the system, and thereafter the object product is recovered bydistillation. Or, in case the object compound is normally in solidstate, it may be recovered as crystals from the distillation residue.The object compound can be also recovered from the reaction mixture orfrom the distillation residue, by means of extraction.

Thus obtained object compound can be further purified if so desired, bysuch known means as distillation or recrystallization.

In the past, no process which achieves single-stage preparation ofaromatic compound containing monoethylenic unsaturated radicals frommonoethylenically unsaturated compound and aromatic compound is known.Whereas, according to the present invention, it is possible to directlyproduce aromatic compound containing monoethylenic unsaturated radicalsfrom the reaction of a monoethylenically unsaturated compound with anaromatic hydrocarbon, in the presence of a palladium salt. Thus theinvention provides an economically very advantageous process.

The object compounds obtained in accordance with the invention arevaluable as monomeric materials for synthetic resins, materials forsynthesis of organic compounds, and intermediates of dyestufis andmedicines. Thus they are used in the fields known per se, being utilizedof their ethylenically unsaturated property.

The invention Will be explained in further details, with reference tothe following working examples.

Example l A 2-liter capacity, three-necked flask with a stirrer andreflux condenser was filled with 340 cc. of benzene, cc. of acetic acid,3.4 g. of styrene and 7.2 g. of palladium acetate, and the content wasboiled under reflux for 6 hours with stirring. After termination of thereaction, the content of the flask was cooled, and whereby precipitatedsolid was filtered. From the filtrate, benzene was distilled off underatmospheric pressure, and then acetic acid, under a reduced pressure (30mm Hg) by means of a water-jet pump, followed by further removal bydistillation of B-acetoxystyrene at a pressure of 5 mm Hg. Thedistillation residue was crystalline, which was recrystallized fromethanol to yield 5.24 g. of a crystalline product having a melting pointranging 122 123 C. The product was identified to be trans-stilbene, bythe results of ultraviolet and infrared absorption spectra tests and ofmixed examination with pure trans-stilbene. The yield was mol percent tothe palladium acetate employed.

EXAMPLE 2 The reaction of Example 1 was repeated except that 7.2 g. ofpalladium acetate was replaced by 7.4 g. of palladium nitrate. Thereaction product was treated in the manner similar to Example 1, and 3.9g. of trans-stilbene was obtained. The yield was 68 mol percent to thepalladium nitrate.

EXAMPLE 3 The reaction of Example 1 was repeated except that 340 cc. ofbenzene was replaced by the same quantity of toluene. The reactionliquid was cooled and the precipitated solid was filtered off. Thefiltrate was washed with water, de-watered and dried with Glaubers salt,removed of a portion of toluene at a reduced pressure and concentrated.Thus concentrated liquid was passed through a column packed with g. ofalumina, and the column was eluted with 500 cc. of petroleum ether and170 cc. of diethyl ether. Thus 3.7 g. of a white crystalline producthaving a melting point ranging from 119 120 C. was obtained, which wasidentified to be transl paramethylphenyl-2-phenylethylene. The yield was58 mol percent to the palladium acetate.

EXAMPLE 4 Example 3 was repeated except that the 340 cc. of toluene wasreplaced by the same quantity of p-xylene. Thus. 3.2 g. of a crystallineproduct melting at 43 44 C. was obtained. This product wastrans-1-(2,5-dimethylphenyl)-2-phenylethylene, and its yield was 47 molpercent to palladium acetate.

' EXAMPLE 5 5.7 grams of palladium chloride, 19 g. of sodium acetate,3.4 g. of styrene, 340 cc. of benzene and 80 cc. of acetic acid werereacted, and the product was treated in the manner similar to Example 1.Thus 4.1 g. of trans-stilbene was obtained, with the yield of 71 molpercent to the palladium chloride.

EXAMPLE 6 Example 5 was repeated except that 19 g. of sodium acetate wasreplaced by 23 g. of potassium acetate. Thus 1.5 g. of trans-stilbenewas obtained with the yield of 30 mol percent to the palladium chloride.

EXAMPLE 7 11.2 grams of palladium acetate, 340 cc. of benzene and 80 cc.of acetic acid were placed in a 2-liter capacity, fournecked flask whichwas equipped with a stirrer and reflux condenser. The system was heatedunder reflux for 8 hours with stirring, while ethylene gas was passedthrough the system at a rate of approximately 40 cc./min.

The reaction product was treated in the manner similar to Example 1, and1.44 g. of trans-stilbene was obtained. The yield was 16 mol percent tothe palladi: m acetate. The styrene formation was confirmed to be 4 molpercent to the palladium acetate, as the result of gas chromatographicanalysis.

EXAMPLE 8 9.1 grams of styrene-palladium dichloride complex prepared byKharash process, 340 cc. of benzene and 80 cc. of acetic acid wereplaced in a 2-liter capacity, three-necked flask, and reacted for 4hours at 80 C. and atmospheric pressure, with thorough stirring. Aftertermination of the reaction, the content of the flask was cooled, andthe precipitated solid was filtered off. From the filtrate, firstbenzene was distilled off at atmospheric pressure, then acetic acid at apressure reduced by a water-jet pump, and finally B-acetoxystyrene at apressure of 5 mm Hg. The distillation residue became crystalline, whichwas recrystallized from ethanol to produce 1.86 g. of a crystallineproduct melting at 122 123 C. The product was confirmed to betrans-stilbene by ultraviolet and infrared absorption spectra tests andmixed examination with pure trans-stilbene. The yield was 32 mol percentto the styrenepalladium dichloride complex employed. As thesideproducts, 0.89 g. of fi-acetoxystyrene and a minor quantity ofresinous matter was obtained.

EXAMPLe 9 33.1 grams of styrene-palladium dichloride complex, 1,000 cc.of toluene and 300 cc. of acetic acid were reacted for 4 hours at 110 C.with thorough stirring in a 2-liter capacity, three-necked flask. Thereaction product was treated in the manner similar to Example 8, toproduce 7.2 g. of a crystalline product melting at 1 19 120 C. Theproduct was identified to be 4-methyl-trans-stilbene, and its yield was32 mol percent to the styrene-palladium dichloride complex employed.Also side-formation of a minor quantity of B-acetoxystyrene wasobserved.

EXAMPLE 10 11.0 grams of cyclohexen-palladium dichloride complex, 350cc. of benzene and 50 cc. of acetic acid were reacted for 7 hours at 80C., with thorough stirring in a 2-liter capacity, three-necked flask.The reaction product was treated in the manner similar to Example 8, and0.34 g. of l-phenylcyclohexene was obtained.

EXAMPLE 1 1 An autoclave of ZOO-cc. capacity was charged with 22.0 g. ofpalladium chloride, 120 cc. of benzene and 13 cc. of acetic acid andfurthermore with ethylene until the inside pressure arose to 70atmospheres. The inside temperature was then raised to 150 C. withstirring, and the reaction was performed for an hour. The reactionproduct was withdrawn from the autoclave after cooling, followed byfiltration. A 4 percent aqueous solution of sodium bicarbonate was addedto the filtrate until the acetic acid was neutralized. Thereafter thesystem was let stand, and the upper lay (benzene layer) was separated,de-watered with magnesium sulfate, and subjected to a reduced pressuredistillation at approximately 200 mm Hg. Thus 0.61 g. of styrene wasobtained. In the reaction, sideformation of vinyl acetate was notobserved.

EXAMPLES l2 29 dicated in Table 1 below, with the results given in thesame table.

The products of Examples 13, 16 and 21 29 were determined and identifiedby means of gas chromatography.

We claim:

1. A process for the preparation of compounds of the formula wherein Xis selected from the group consisting of hydrogen,

halogen, alkyl of one to four carbon atoms, phenyl and alkylsubstitutedphenyl,

Y is selected from the group consisting of hydrogen, alkyl of one tofour carbon atoms, phenyl, alkyl-substituted phenyl, nitrile, alkoxy ofone to four carbon atoms, halogen, alkoxycarbonyl and alkanoyloxy of twoto four carbon atoms,

Z is selected from the group consisting of hydrogen, alkyl of one to 12carbon atoms, nitro, halogen, alkoxy of one to 12 carbon atoms andalkoxycarbonyl and n is the integer 1 or 2,

which comprises reacting a compound of the formula wherein X and Y havethe above definitions, with a compound of the formula wherein Z and nhave the above definitions, in the presence of a palladium salt of analiphatic monocarboxylic acid of one to five carbon atoms or a mixtureof a palladium salt selected from the group consisting of halides,sulfate and nitrate of palladium with an alkali metal salt of analiphatic monocarboxylic acid of one to five carbon atoms.

2. The process of claim 1, in which the palladium salt is present in thereaction system in a quantity of at least fourth mol per mol of themonoethylenically unsaturated compound.

3. The process of claim 1, in which the reaction is performed in analiphatic monocarboxylic acid of one to five carbons as solvent.

4. The process of claim 1, in which the reaction is performed attemperatures ranging from room temperature to 200 C.

5. The process of claim 1, in which the palladium salt is palladiumacetate.

6. The process of claim 1, in which the monoethylenically unsaturatedcompound is selected from the group consisting of ethylene, propylene,vinyl fluoride, acrylonitrile, butyl vinyl ether, vinyl acetate,styrene, 4-methylstyrene, and 1,1-diphenylethylene and cyclohexane.

7. The process of claim 1, in which the aromatic compound is selectedfrom the group consisting of benzene, toluene, xylene,monochlorobenzene, mononitrobenzene, monoethylbenzene, and anisole.

7 8. The process according to claim 1 wherein X, Y and Z are eachhydrogen and n is l.

9. The process according to claim 1, wherein X and Z are each hydrogen,Y is phenyl and n is 1.

10. The process according to claim 1, wherein X is 75 hydrogen, Y isphenyl, Z is methyl and n is 1.

2. The process of claim 1, in which the palladium salt is present in thereaction system in a quantity of at least fourth mol per mol of themonoethylenically unsaturated compound.
 3. The process of claim 1, inwhich the reaction is performed in an aliphatic monocarboxylic acid ofone to five carbons as solvent.
 4. The process of claim 1, in which thereaction is performed at temperatures ranging from room temperature to200* C.
 5. The process of claim 1, in which the palladium salt ispalladium acetate.
 6. The process of claim 1, in which themonoethylenically unsaturated compound is selected from the groupconsisting of ethylene, propylene, vinyl fluoride, acrylonitrile, butylvinyl ether, vinyl acetate, styrene, 4-methylstyrene, and1,1-diphenylethylene and cyclohexane.
 7. The process of claim 1, inwhich the aromatic compound is selected from the group consisting ofbenzene, toluene, xylene, monochlorobenzene, mononitrobenzene,monoethylbenzene, and anisole.
 8. The process according to claim 1wherein X, Y and Z are each hydrogen and n is
 1. 9. The processaccording to claim 1, wherein X and Z are each hydrogen, Y is phenyl andn is
 1. 10. The process according to claim 1, wherein X is hydrogen, Yis phenyl, Z is methyl and n is 1.